The disclosure relates to an angle sensor for ascertaining an angle of rotation of a rotatable body, which angle sensor can be used in particular as a steering wheel sensor to ascertain a steering angle of a steering column in a motor vehicle. The disclosure further relates to a toothed wheel for an angle sensor of this type and to a method for producing a toothed wheel of this type.
Angle sensors are known that are embodied to obtain an absolute measurement of an angle of a rotatable body, i.e. also when the body is not moving. An angle sensor of this type is known from DE 195 06 938 A1. In this case, a first toothed wheel is provided on a rotatable body, for example a steering column of a vehicle, which first toothed wheel can co-rotate with the rotatable body by more than 360°. Two measuring toothed wheels mesh with this toothed wheel, wherein the number of teeth of these measuring toothed wheels is less than in the case of a previously known toothed wheel and the number of teeth differs in the case of the two measuring toothed wheels for example by one tooth. It is possible to ascertain an absolute measurement of the angle of the first toothed wheel from the measured angles of the two measuring toothed wheels and consequently to ascertain the angle of the rotatable body.
In order to be able to ascertain the angle of measuring toothed wheels, said toothed wheels comprise magnetic pills in the case of conventional angle sensors. These magnetic pills are embodied from a magnetizable material, for example NdFeB (neodymium iron boron) and/or a moldable matrix material in which the NdFeB particles are embedded. A magnetic pill is fixedly connected to the measuring toothed wheel. The magnetic pill can, for example, be clipped into the toothed wheel. Alternatively, in order to produce the entire measuring toothed wheel, a magnetic pill can be provided as a core and injection molding is performed around said core in the remaining measuring toothed wheel during the injection molding process.
The orientation of the magnetic field that is generated by the magnetic pill can be measured with the aid of a magnetic field sensor that is arranged adjacent to an end face of the measuring toothed wheel. The orientation of the respective measuring toothed wheel can be ascertained from the orientation of this magnetic field and it is ultimately possible with the knowledge of the two orientations of the two measuring toothed wheels to ascertain the orientation and/or the angle of rotation of the rotatable body.